District of



(No Model.)

W. H. HARRIS 8v J. C. KAFER.

l ATTAGHMENTFOR BOILBB, PURNAGES. No. 373,557.

Patented Nov. 22, 1887.

wimowa N, PETERS. Phono-Lichagmphr, whingmn. D. C.

- UNrTnn STATES WILLIAM H. HARRIS AND JOHN C. KAFER, OF WASHINGTON,DISTRICT OF COLUMBIA.

ATTACHMENT Foa soiree-r-'LJRr\1AeF s.v

'SPECIFICATION forming part of Letters Patent No. 373,557, datedNevember 22, 1887.

(No model.)

T all whom it may concern:

Be it known that we, WILLIAM H. HARRIS and JOHN C. KAFER, citizens ofthe United States, residing at Washington, in the District of Columbia,have invented a new and useful Improvement in Attachments toBoiler-Furnaces, of which the following is a full, clear, and exactdescription.

This invention relates to improvements 'in ro devices to prevent theleakage of gases from the furnace and feeding air to furnaces whenoperated under forced draft,or where the pressure of air under the grateis greater than the atmospheric pressure.

t5 The object is to prevent the gases from a furnace having a closed ashpit and forced draft being forced through the openings around thefurnace-door into the fire-room. The air entering the ash-pit is freelyadmitted to the 2o Space between the inner and outer plates of thefurnace door, and as this air is under a higher pressure than the air orgases in the furnace the air between the inner and outer plates ofthefurnace-door will be forced into the furnace on one side and into thetire-room on the other, preventing the escape of' gases from the furnaceand keeping the furnacedoor cool.

It will be understood that this is not intended. as an air-feedingdevice for supplying air to the furnace through the furnace-door, butthat the special object is to keep a sufficient pressure of air insideof the door and between its walls to prevent the passage offurnace-gases from the furnace into the fireroom. The leakage of airfrom within the door into the furnace and tire-room will be only what isdue to the fact that the door will ordinarily fit loosely in its frame,unless more air is required over the fuel, when air can be suppliedthrough holes in the inner plate of the furnace-door or furnace-front,as is now donein furnace-doors and furnace-fronts using a natural draft.

Vhen it is necessary to open the furnacedoor for any purpose while usingforced draft, the damper in the air-pipe leading to the ashpit is firstclosed, reducing the pressure in the furnace. Then thefurnace doorcan beopened and the furnace operated as when using nat- 5o ural draft.

The ash-pit is closed by a door made tight by a gasket or other means,and provided with suitable means for securing the door.

The damper is operated from the outside of the air pipe or boX, therebeing a damper to each ash-pit or furnace. By closing the damper theair-pressure in the furnace to which it is connected is reduced, thefurnace-door may be opened, and the tire cleaned or coaled,while 6o thepressure in the ash-pits of other furnaces is not reduced, butmaintained to the maximum of air-pressure supplied by the blowers.

rlhe method of increasing the combustion by forcing air intoan air-tighttire-room, or properly a closed tire-room, has the objections that it isdifficult to make the bulk-heads perfectly air-tight; that air-locks arerequired for the ingress and egress of remen; that the airpressure israpidly reduced when a furnacedooris opened, and that the cold airrushing in the furnace when the furnace-door is open impinges on thetube-sheets and tubes, causing contraction of the metal and the seamsand tubes to leak, while the air-pressure in the fireroom is reduced,lessening the rate of combustion in the other furnaces. Blowing the airunder the grate obviates these difficulties; but when theairpressure isincreased to such an extent as to make the pressure in the furnace 8ogreater than the normal pressure ofthe atmosphere the gases are forcedinto the fire-room through the cracks and openings around thefurnace-door and frame, making the door redhot and the atmosphere of thefire-room unbearable.

' To prevent the escape of the furnace gases when using a closedash-pit, a combination of the two systems has been used, having a closedash-pit with air-pressure under the grates and 9o a closed fire-roomwith an air-pressure in the fire-room greater than the pressure ofthegases in the furnace, but less than the pressure under the gratesin theclosed ash-pit. The press` ure in the furnace is less than the pressureunder the grates on account of the resistance of the fuel to the passageof the air. When the furnace-door is opened, the pressure of air in thefire-room being about the same as the furnace gases, there is no greatinflow of cold air or outflow ofgases; but with this combination'thefire-room is not properlyventilated and the heat becomes unbearable.

By our invention the difficulties ofthe closed fire-room, the closedash-pit, and the combination of the two systems are avoided, thuspermitting an open fire-room for the ingress and egress of the firemen,free ventilation of the fire-room, while a high air-pressure can bemaintained under the grates and in the furnaces without forcing thefurnace gases into the fire-room.

Reference is made to the accompanying drawings, formingpartofthisspecification,'in which similar letters refer to similar partsthroughout the several views.

Figure lis a section through the furnace, ash-pit, furnace-front,furnace-door, air pipe or box, damper, and ash-pit door. Fig. 2 is apartial front elevation and a partial section through thefurnace-frontand air pipe or box.

A represents the furnace; B, the ash-pit; C, the air pipe or box; D, thefurnace-door, with double plates J and K; E, the furnace-front anddoor-frame, with the passageFand openings H to admit air under pressurefrom the ash-pit B or air-box C, through the passage F and H, to thespace between the front and back plates forming the furnace-front and tothe space between the two plates J K of the furnaceldoor, therebyair-packing the furnacedoor and preventing any leakage of gases from thefurnace to the fire-room, also providing for a leakage of air from thespaces between the two plates forming the furnace-door to` the furnaceand to the fire-room, ifthere is any opening in the furnace-door,thereby keeping the furnace-door cool. The openings H'may be of anyconvenient form or size and as near to eachother or as far apart as maybe desired.

P is the dead-plate. r

L is the damper in the air-box C, to be 0perated by the lever N, orothersuitable means.

M is the ash-pit door, secured to the front of the ash-pit or projectionof' the furnace by the movable clamps O, or other suitable means.

R is a deflecting-plate to defiect the air to the openings in thedead-plate and furnacefront.

When the forced draft is not used, this ash-- pit door can be removedfrom the front of each ash-pit and the furnaces operated under naturaldraft.

The ash-pit door is to be made air-tight, or sufficiently so to preventany great leakage of air from the ash-pit to the tire-room, by a gasketor other suitable means.

Having thus described our invention, what we claim as new, and desire tosecure by Letters Patent, is-

l. The method of preventing the escape of furnace-gases from the furnaceof a steamboiler into the fire-room around the furnacedoor byair-packing the door, consisting in supplying air under pressure fromthe ash-pit through openings inthe door-frame or furnace-front anddead-plate, wholly or partly inside the furnace, to the space betweeninner and outer plates of the furnace-door and doorframe orfurnace-front, substantially as shown and described.

2. The combination of the furnace-door D, formed of plates separated toform an airchamber for air under pressure from the ashpit, with thehollow door-frame or furnacefront E, wholly or partly inside thefurnace,

' perforated in the arch with openings H,to supply air to said chamberfrom the ash-pit, and the perforated dead-plate P, with openings fromthe ash-pit to supply air from it to the space between the plates ofdoor and to the hollow door-frame orfurnace-front, substantially asshown and set forth.

3. The combination of the hollow perforated I door-frame E with thepassages F, the hollow furnace-door D, the perforated dead-plate P, theopenings in the dead-plate between. the ash-pit and the air-chamberformed by the door, the air-duct C, leading to the ash-pit, and thedamper L, for closing the duct O, substantially as shown'and set forth.

4. The combination of' the hollow furnacedoor D, having, When closed,its interior in communication with the closed ash-pit B 'throughopenings in the door-frame or furnace-front and dead-plate, by which airunder pressure may be supplied from the closed ashpit for the purpose ofair-packing the furnacedoor and preventing the escape of furnacegasesthrough or around the furnace-door into the fire-room, substantially asshown and set forth.

5. The combination of the furnace-front E, with passage F and openingsH, the furnacedoor D, the closed ash-pit B, the deflectingplate R, theair pipe or duct C, the damper L, the lever N, and'the ash-pit door M,in connection with a boiler operated under forced' draft, for thepurpose specified.

WILLIAM H. HARRIS. JOHN C. KAFER. Witnesses:

MARTIN BEVINGTON, WM. H. NAUMAR.

IOO

IIO

